function [r, dr] = calRandDR(state)
x = state(1);
y = state(2);
z = state(3);
V = state(4);
fpa = state(5);
azi = state(6);

SMT = sqrt(x^2+y^2);
r = sqrt(x^2+y^2+z^2);
lambda = atan(z/SMT);
if x >= 0 
    phi = asin(y/SMT);
else
    phi = -(asin(y/SMT)+pi);
end
dr = V*(sin(phi+azi)*cos(lambda)*cos(fpa)+sin(lambda)*sin(fpa));
end

